Area of the Invention
The present invention relates to a distance information producing apparatus that produces, by a pupil-division phase difference detection method, distance information showing a distribution of object distances.
Description of the Related Art
A method of producing a distance map showing a distribution of object distances in an image capturing scene (image capturing area) from a captured image acquired by an image capturing apparatus has been conventionally proposed.
Japanese Patent Laid-Open No. 2013-239119 discloses a method of producing a distance map by a Depth from Defocus (DFD) method. The DFD method estimates an object distance from difference in blur in multiple images whose focal positions are mutually different. Japanese Patent Laid-Open No. 2013-239119 further discloses a method of producing a reliability map showing a reliability for the produced distance map. Specifically, the disclosed method divides an in-focus image that is an input image into multiple rectangular areas and analyzes whether or not each divided area has a small luminance change. Then, the disclosed method calculates a lower reliability for the divided area having a small luminance change, as compared to that for a divided area having a large luminance change. The disclosed method further corrects the distance map by using the reliability map and performs, with referring to the corrected distance map, a process to produce an image having a large depth of area from an image having a small depth of area.
On the other hand, Japanese Patent Laid-Open No. 01-216306 discloses a focus detecting apparatus configured to detect (calculate) a defocus amount of an image capturing lens, from a relative shift amount (phase difference) between paired object images formed by paired light fluxes passing through mutually different pupil areas in an exit pupil of the image capturing lens. Such a method that calculates the defocus amount from the phase difference of the paired object images provided by dividing the exit pupil is called a pupil-division phase difference detection method.
Utilizing the pupil-division phase difference detection method disclosed in Japanese Patent Laid-Open No. 01-216306 enables producing the distance map disclosed in Japanese Patent Laid-Open No. 2013-239119. However, Japanese Patent Laid-Open Nos. 2013-239119 and 01-216306 do not disclose a method of producing the above-mentioned reliability map corresponding to the distance map produced by utilizing the pupil-division phase difference detection method.